Human Pathology Reports (Jun 2022)
Lesions of the nipple
Abstract
The nipple-areolar complex is anatomically unique, and certain breast lesions are found only at this site. The epidermis may be involved by ductal carcinoma in situ (Paget disease), which is usually morphologically high grade; immunohistochemical stains for HER2 and CK7 are useful for distinguishing Paget disease from Toker cells and melanocytic populations. Benign epithelial proliferations can give rise to nipple adenomas and large duct papillomas, which may appear focally infiltrative. Identification of an associated myoepithelial cell layer prevents an incorrect diagnosis of invasive carcinoma. Large superficial ducts may become filled and expanded by keratinous plugs resulting in squamous metaplasia of lactiferous ducts. Elements within the underlying stroma may rarely beget neural and smooth muscle tumors.
